camera recommendations?

[Rebecca Lundwall]

Yes, EPrime support helped me, but it took a lot of back and forth. We
ended up switching back to a parallel port device that I got from Horita in
order to inject a time stamp on the video capture, doing video capture on a
2nd CPU etc. We did not go with low light as that apparently interferes
with frame rate capture. 60 Hz seems to be working fine.

I don't know how to do time stamp with a webcam and would be linked to the
presentation of each new stimulus. If you are thinking of buying a
camcorder and a time stamp device then I will let you know further details.




On Wed, May 7, 2014 at 12:18 PM, John Goodrich <marcgoodrich5 at gmail.com>wrote:

> Hi Rebecca,
>
> I see that no one ever responded to your post, but did you ever figure out
> a solution to this problem? I am designing a preferential looking task that
> seems similar to the task you described, only I am using a webcam to record
> the eye movements. I would like to be able to have E-Prime tell the webcam
> to start recording when the experiment begins so that the onset times of
> objects in the E-Prime output can be directly used to identify when in the
> video the two images appear to let me know when to begin coding eye
> movements.
>
> Thanks,
>
> John Goodrich
>
>
> On Friday, October 18, 2013 10:21:29 PM UTC-4, Rebecca Lundwall wrote:
>>
>> I am trying to get a new research lab set up. I use EPrime to present
>> stimuli and a camera to collect eye movement data. I am working with the
>> college's computer services and they asked me to contact this group and see
>> if you had recommendations on *camera specs* for the following situation.
>> PSTNET support also suggested that I ask this question here. I do not use
>> eye-tracking equipment because it does not work well with young infants.
>>
>> My question is if anyone knows of a camera or camera set-up that would
>> work without the ForA timer. My key concern is having a time-stamp on the
>> video and that the time-stamp is controlled (started and stopped) by EPrime
>> presenting the stimulus. I will describe how we have done this in the past,
>> but I can no longer find a supported For-A video timer VTG-33 (which
>> reports frames) and we are nervous about buying the one I found on Ebay.
>>
>> In the experiment:
>> 1) E-Prime simultaneously sends an image to a monitor and starts the ForA
>> timer (or it could start the camera's timer)
>> 2) The ForA timer (if used) puts a time stamp on the digital video
>> recording. The timestamp starts and runs until EPrime tells it to stop.
>> Stopping the clock is important so that trials are separated and RAs don't
>> get confused when they go back and code for eye movement latency and
>> direction (left or right). If I used the camera's internal clock, EPrime
>> would need to start and stop it's clock or start and stop the entire camera.
>> 3) the digital video with the time stamp are sent back for storage on the
>> computer
>> 4) the digital files are opened  with a video editing software) that can
>> detect scenes based on lighting conditions (the presentation of a new
>> stimulus triggers a new scene); we number the scenes and two RAs code them
>> for eye movement latency and direction.
>>
>> So, does anyone know of a camera that has a timestamp down to the frame
>> level and that can be synced with the presentation of a stimuli by EPrime?
>> Other info or related questions:
>> *the camera must work in low-light conditions
>> *there are approximately 50-60 trials for infants and 200 for children,
>> each is presented for between 67 msec - 4 sec
>> *I care about response differences as small as 10-20 msec (so am thinking
>> about a camera with 60 fps or more)
>> *is 60 Hz sufficient for the CPU?  If I get more fps on the camera do I
>> need higher refresh rate as well?
>>
>> Thanks for your help.
>>
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